Heat transfer device



R. s. GAUGLER HEAT TRANSFER DEVICE Filed Dec. 21,1942

June 6, 1944.

J INVENTOR.

Patented June 6, 1944 HEAT TRANSFER DEVICE Richard S. Ganglcr, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application December 21', 1942, Serial No. 469,649'

(Cl. 62l25) 12 Claims.

My invention relates'to the art of transferrlngheat and particularly to a method of and apparatus for transferring heat from one point to another.

In the art of transferring heat from one point to another, itis common practice to use a closed system partially .fllled with a volatile liquid wherein heatis absorbed at one point by the evaporation of the volatile liquid and wherein heat is dissipated or given off at another point by the condensation of the vapor to a liquid. In' such systems, as far as I am aware, the evaporation of the liquid or, ii. other words, the absorption of heat always takes place at an elevation below the point where condensation, or in other words the giving off of heat, takes place,-unless some additional work'is expended on the liquid to lift it as a liquid to an elevation above the point where condensation 'takes place. 7

It is the principal object of my invention to cause anabsorption of heat, or in other words,

the evaporation of the liquid to a point above the place where the condensation or the givi of! of heat takes place without. expending upon the ment 22 which is to be maintained at a low temperature. Removably attached to the underside of the refrigerator by means of the wing nuts, 21 is a pan 26 containing cracked ice. Through the lower wall of the refrigerator extends the. tube 24 hereinafter more fully described.

The sealed tube 24 comprising the means for transferring heat from the insulated compartment 22 to the cracked ice within the container 26 is disclosed in some detail in Figs. 2, 3, 4, and 5. As shown in Figs. 2 and 3, one embodiment of this device comprises a vertical tube 28' pinched shut at its upper end and at its lower end .opening into a short horizontal tube 30 which is likewise in the form of a sealed container. -Thehorizontal tube 30 is provided with a fin 32 to increase its area of contact with the cracked ice and water in the pan 2. The horizontal tube 30 is partially filled with a volatile.

liquid 34. All other gases and liquids as far as possible are removed from the container formed by the tubes 28 and 30. The presence of other 1 gases and liquids will not render the device inliquid any additional work to lift the liquidto an elevation above the point at which condensation takes place.

In accomplishing the aforesaid principal object of my invention, other more specific objects will be attained and these more specificobiects will be apparent from the following description taken with the drawing, wherein: Y

Fig. 1 is a sectional view of a novel form of refrigerator embodying one application of my method and apparatus for transferring heat;

Fig. 2 is an enlarged sectional view taken along the lines 2-2 of Fig. 1;

3 is an enlarged sectional view taken along the lines 3-3 of Fig. 2;

Fig. 4 is a sectional view similar to Fig. 3 illustrating amodified form of the invention; Fig. 5 is another cross-sectional view .similar to Fig. 3 showing another form of the invention;

and

Fig. 6 is a sectional view of a twocompartment refrigerator embodying another application of my method and apparatus.

For the purpose of illustrating one way in which my invention maybe used, I have shown my novel method and apparatus for transferring heatas applied tothe cooling of the interior of.

a refrigerator. For instance, in Fig; l, the reference numeral diagrammatically illustrates an insulated refrigerator containing the compartoperative but will raise the temperature diiferential. It is'desirable that the liquid chosen for this purpose have a high latent heat of evaporation, a low density and low molecular weight, together with a high surface tension. Substantially any volatile liquid will work to some extent.

Some examples of such liquids are anhydrous arnm onia,.water, and ethyl and methyl alcohol.

The heat, transfer device as so far described, would not operate to cool eilloiently the interior of the compartment 22. vThere would only be a comparatively slight transfer of heat from the compartment 22 to the cracked ice and water in the pan 26 by means of direct thermal conduction through the metal walls of the tube 28. The liquid 34 will naturally collect at the lowest part of the container. The vapor within the sealed tube .24 will tend to condense in the coldest portion thereof which will naturally be the portion immersed in the cracked ice and water in the pan 26. Heretofore it has been necessary to use forced circulation or to arrange such a heat transfer device so that the coldest portion is at the top and the warm portion below, so that the liquid will collect in the warm portion and evaporate and the vapor will condense on the colder upper portions. Such an arrangement with the coldest portion at the top is very inconvenient for some purposes and cannot be used where the sourcebi heat is at a level above the source of cold.

' I, however, have found a very simple way to temperatures to which this portion of the tube 28 make such a heat transfer devicehoperate no and the capillary structurefliare subjectedwith;,--fil"V matter what is the relationship 'ih ele atibirbe in the com artm This evaporated volav tween the source of heat and the source of cold. tile liquid will collect in the upper portion of the To do this, I provide a means which will carry tube and by progressive accumulation there, will the liquid upwardly or in any direction without be forced down through the passage 38 provided any forced circulation and without any moving at the side of the porous capillary structure 36 parts. This means is in the form of a capillary to the bottom of the tube 28 and escape through structure 36 which extends from beneath the the liquid 34 to the space abovetheliquid 34 surface of the volatile liquid 34 up through the where it will condense upon thelwalls of the t'k tube 28 substantially to its top or as far as is -30. Thus, by this principle, I transmit heat desirable to carry the cooling effect. downwardlyv through evaporation and condensa- I have found that many capillary means may tion and raise liquid upwardly without the exbe used for this purposer l hewhoicenof the penditure of any work in raising the liquid. capillary means depends upon the liquid and the TNhe -construction shown in Fig. 4 may also be vertical height to which the liquid is to be raised. used in this heat transfer device. The tube 8 For example, with a liquid such as anhydrous is provided with a capillary structure 56 formed ammonia there may be used a continuous porous in three parts e clo ng a t i gular pass capillary structure of sintered powdered iron. 58. In this form, the sintered iron may be made Such a capillary structure may be formed by in the form of a paste and lightly pressed against mixing non-compacted iron powder with ferrothe walls of the .tube and baked prior to the ph phorus powder to give a'final or completed sintering-process. Where it is desired that there product containing 1.8% phosphorusi I prefer be lessconduction' between the walls of the tube. iron powder of substantially pure iron of such a. and the porous capillary structure, the form size that all will pass through a 250 mesh screen Shown in -5 y b u In this form, the and none will pass through a 325 mesh screen. ap y Structure in the form of a q r To provide the capillary structure 36 the proper rod with corners rounded as much as is desired mixture of iron and ferro-phosphorus powder to give the desired contact with the inside wall is placed in the tube 28 with a m ll spacer of the tube is sintered in a mold and then inserted tending the full length of the tub an placed in into the tube 68 after the sintering process is a horizontal position, after which the spacer is Completed s construction SeDeIeteS t withdrawn and the tube kept in a horizontal greater t n of t e api a y st uct r 611 position while it is placed in a furnace. The furt Wells the tube 68 by h fo r s t nti l y nace is preferably maintained at a temperature identical P e 8 hich are formed bet ee between 1950 and 2100 F. for periods rangin the flat sides ofthe capillary structure and the from about fifteen m ut t one hour, The inner walls of the tube 68. In each of these moditube preferably should be maintained under nonficetions Shown in Figs- 4 a d the P s s 55 oxidizing conditions while it is heated and cooled, and 18 correspond to the passage 38, while the Where carbon-fr e i o powder cannot b bcapillary structures 56 and .16 correspond to the tainedit is preferable to sinter under de-car- 4o. capillary st e while the tubes 48 and bonizing conditions whereby the finished sintered correspond to the t material is substantially free from carbon. This In Fig. 6, I have shown my invention app i sinterlng provides a porous homogeneous struce to a two-compartment refrigerator I20 contain ture having great capillary attraction whi h i ing in the. lower-portion of the insulated cabi firmly bonded to the adjacent walls of the tube a freezing compartment enclosed by w 28. After this is done, the tube 28 is joined by inner liner around which is Wrapped tubi, s a seal joint to the tube at and the entire struc- I26 constituting the primary evaporator vture-evacuated after which the volatile liquid Primary erating system which includes a is inserted and th upper end of t t 1 is sealed motor-compressor unit I28 forwithdrawpinched ofi to seal the container. Sufficient vols evaporated refrigerant om t p y atileliquid should be inserted tofill the porous evaporator d for o a d g t e co capillary structure and in addition provide a pool pressed refriger n to a condenser Where the of sufli ie t depth in t t 30 t nt the compressed refrigerant is liquefied and returned bottom oi'the capillary structure under all condit0 the evaporator under e control of a tions. Prior to assembly, the lower end of the Suitable expansiim Valve This Primary tube 28 may becut ofito expose the lower end frigerating circuit is shown diagrammatically of the capillarystructure 36 so that it may prothe Purpose of'illustl'etiontrude below the end of the tube 28 and project 'ihe'insul ted cabinet is also provided with an further into the .liquid 3L However, this is not upper compartment I34 which is to be mainnecessary and good results can be obtained ta n d t a t a r s htly a ove r n without this. I such as 35 or 40 F. Particularlydt is desired Briqu tt d r compacted powdered metal with that none of the atmosphere in this compartment or without sintering may beused if desired but cehteets any Surface belOW and i is dewith a, redu q volume ofoapillary flow due t sired that the cooling of this compartment be the reduced porosity. Also, iron, cobalt, or nickel 05 c mp wi h minimum difierential bepowder may be used with' either iron, cobalt, "or tween the desired temperature of the atmosphere nickel phosphorus powder. In general, any coni and the temperature of the refrigerating surfaces tinuous porous capillary structure will give rey which it is cooled a 1 suits in accordance with its ability to provide a To cool the walls of the inner liner I36 which flow of liquid inany direction due to capillary 7o encloses this upper compartment 134, I use a action, I number of my improved heat'transfer devices In operation, the volatile liquid 34, due to capillike that shown in Fig. 2, with the lower ends or lary action, will climb up through the porous the heat transfer devices elongated and resting capillary structure 36 to the upper part of the in good thermal contact upon the primary evapo-- tube 28 where it will evaporate under the higher a crjifi and thei uppe en s extend up over the sides and bent over the top of the inner liner I36 in good thermal contact therewith. These devices are designated by the reference character I38. By this arrangement, the volatile liquid in the bottom of each tube rises upwardly through the porous capillary structure and comes into heat exchange relation with the sides and top of the inner liner structure where it is heated and evaporates and is forced down through the passage in the tube to the bottom tube which rests on the primary evaporator, where it is condensed. This action takes place in each of the devices and asmany of the devices as closely spaced as is .necessary may be used to maintain the compartment I34 at the desired temperature. These heat transfer devices therefore provide a'simple way in which the compartments of a refrigerator may be arranged for greater convenience and greater thermal eiliciency by placing the warmer compartment, which is usedmost, at a convenient height directly above the colder compartment.

Thus, with the simple heat transfer device shown in Fig. 2, I am able to transfer heat downwardly or. in any direction without any moving parts or forced circulation. It is evident that its use is not limited to refrigeration but that it may be used wherever it is desired to transfer heat at any desired temperatures for any desired purpose. v

While. the form of embodiment of the invention as herein disclosed, constitutes a preferred form,

it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. The method of transferring heat from one point to another by means of a closed system wherein a volatile liquid is successively evapo-- rated and condensed at substantially the same pressure which comprises evaporating the liquid refrigerant at one level, condensing the vapor at another level below the point at which evaporation takes place, and returning the liquid from the point of condensation to the point of evaporation by capillary action.

2. The method of transferring heat from a first point at a higher temperature to a second point at a lower temperature in any. desired direction employing a sealed system containing a volatile liquid which comprises evaporating the volatile liquid at the first point at the higher temperature in the system, condensing the vapor from the volatile liquid at the second point at a lower temperature in the system. and returning by capillary action the condensed volatile liquid from the second point to the first point.

3. Refrigerating apparatus comprising a primary refrigerating means, a device to be cooled .located above said primary refrigerating means,

a sealed container having a first portion in heat exchange-relationship with said primary refrigerating means and a second portion extending into heat exchange relation with said device to be means.

5. A heat transfer device comprising a sealed container means having two points exposedto two different temperatures, said container means containing a capillary means extending continuously from oneof said points to the other and also containing a connecting passage extending between said points, the surface of the capillary means between said points being. exposed to said passage, said container means being provided with a volatile liquid in contact with said capillary means, said capillary means being in the form of non-compacted sintered iron powder bonded to the walls of the container means.

6. A heat transfer device comprising a. sealed container means having two points exposed to two different temperatures, said container means containinga capillary means extending continuously from one of said points to the other and also containing a connecting passage extending between said points, the surface of the capillary means between said points being exposeffto said passage, said container means being provided with a volatile liquid in contact with said capillary means, said capillary means being in the form of non-compacted iron powder bonded together and to the walls of the container means by ferrophosphorus. I

7AA secondary heat transfer device wherein a volatile liquid evaporates at a temperature equal to or greater than the temperatur at which it condenses, comprising sealed container means having two different points exposed to two different temperatures and capillary means extending within the container means continuously from one of the points to the other, one ofsaid means being provided with apassage connecting said points, said capillary means having'its surface exposed to said passage adjacent said pointaand said container means containing a volatile liquid in contact with said capillary means.

B. A secondary heat transfer device wherein a volatile liquid evaporates at a temperature equal to or greater than the temperature at which it condenses, comprising sealed container means having two different points exposed to two different temperatures and capillary means extending within the container means continuously from one of the points to the other, one of said means being provided with a passage connecting said points, said capillary meanshaving its surface exposed to said passage adjacent said points, said container means containing a volatile liquid in contact with said capillary means, and said capillary means being in the form ofa porous metal structure.

9. A secondary heat transfer device wherein a volatile liquid evaporates at a. temperature equal to; or greater than the temperature at which it cooled, said containercontaining a capillary means and a passage each extending continuous- -ly from said first to said second portion. said containe also containing a volatile liquid tact with said capillary means.

4. Heat transfer apparatus comprising a primary heat source, a device for receiving heat loin concondenses, comprising sealed container means having two points exposed to two different temlary means extending continuously from one of cat-ed below said primary heat source, a sealed container having a first portion for receiving heat from said primary heat source and a second portion for transferring heat to said device, said container containing a capillary means and a passaid points to the other and also containing a connecting passage extending between said points, the capillary means having a portion of its sur-= face between. said points exposed to said passage, and said container means being provided with a volatile liquid in contact with said capillary means.

10. A secondary heat transfer device wherein a volatile liquid evaporates at a temperature equal to or greater than the temperature at which it condenses, comprising sealed container means having two points exposed to two different temperatures, said container meanscontaining capillary means extending continuously from one of said points to the other and also containing a connecting passage extending between said points, the capillary means having a portion of its surface between said points exposed to said passage, said container means being provided with a volatile liquid in contact with said capillary means, and said capillarymeans being in the form of a porous metal structure.

11. A secondary heat transfer device wherein a volatile liquid evaporates at a temperature equal to or greater than the temperature at which it condenses, comprising sealed container means having two points exposed to two different temperatures, said container means containing capillary means extending continuously from one of said points 'to' the other and also containing a connecting passage; extending between said points, the capillary means having a portion of its suri'ace between said points exposed to said pass- 1 sage, said container means being provided with a volatile liquid in contact with said capillary means, and said capillary means being in the form of sintered metal.

12. A secondary heat transfer device wherein a volatile liquid evaporates at a temperature equal. to or greater than the temperature at which it 

